Earth's Atmosphere

78% Nitrogen21% Oxygen

gas is ionized by solar radiation

ozone is O3 , which

absorbs solar UV efficiently, thusheating stratosphere

commercial jet altitudes

temperature on a cool day

Original gases disappeared. Atmosphere is mostly due to volcanoes and plants!

Ozone Hole over Antarctica

Led to banning of Chlorofluorocarbons worldwide

Had been used in refrigerators/air conditioners, aerosol cans, and as a cleaning solvent

Rescue Balls and What landed in Roswell

Clicker Question:

A leading cause of Global Warming is:

A: Increased soot (smog) in the atmosphere.

B: Increased carbon dioxide in the atmosphere.

C: The Earth is getting closer to the sun.

D: The luminosity of the sun is steadily increasing.

CO2 in Atmosphere and Temperature

CO2 in Atmosphere

Temperature Predictions

.

Alaska is Ground ZeroAlaska is Ground Zero

Chapman and Walsh, 2004

In past 50 years,

Alaska: Temperatures haveincreased

• 4oF overall(National Assessment Synthesis Team)

Worldwide:Temperatures haveincreased

• Slightly more than 1oF

(IPCC 2007)

Surface Air Temperature Trends 1942-2003

Global Warming BasicsG

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Chapman and Walsh, 2004

Snow and sea ice reflect 85-90% of sun’s energy.

Ocean surface and dark soil reflect only

10-20%.

The Albedo Effect

“White shirt versus Black shirt”

Why has Alaska warmed the most?Why has Alaska warmed the most?

Increased melting of snow

and sea ice

Increased melting of snow

and sea ice

More of sun’s heat energy is

absorbed

More of sun’s heat energy is

absorbed

More dark earthand ocean surface

is exposed

More dark earthand ocean surface

is exposedLand or water warms faster

Land or water warms faster

Global Warming BasicsG

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(ACIA 2004)

Source ACIA, 2004Jennifer Allen Animation

An area twice the size of Texas has melted away since 1979 (over 20%

decrease). (National Snow and

Ice Data Center 2005)

Ice 40% thinner. (Rothrock,D.A, et al. 1999)

Ice only 6 – 9 feet thick at North Pole (NOAA FAQ 2007).

Northwest passage opened Aug 21, 2007

Impacts in Alaska1. Melting

Melting Sea IceMelting Sea Ice

1978 1983 1988 1993 1998 2003

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ARCTIC SEA ICE AREA1979-2005

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Impacts in Alaska1. Melting

The rapid retreat of Alaska’s glaciers represents about 50% of the estimated mass loss by glaciers through 2004 worldwide. (ACIA 2004)

Loss of over 588 billion cubic yards between ’61 and ’98. (Climate Change 11/05)

Alaska’s glaciers are responsible for at least 9% of the global sea level rise in the past century. (ACIA 2004)

19411941

20042004

Glacier Bay (Riggs Glacier)

USGS photo

Bruce Molnia photo

Glacial RetreatGlacial Retreat

20032003

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19581958

McCall Glacier

• Polar bears• Walruses• Ice seals• Black guillemots• Kittiwakes• Salmon• Caribou• Arctic grayling

Impacts in Alaska3. Animals

Animals at RiskAnimals at Risk

Rising temperatures

Shrinking habitat

Food harder to get

Expanding diseases

Competition

Polar bearsWalrusesIce seals

Caribou

Black guillemotsKittiwakesSalmon

Arctic grayling

Ocean AcidificationOcean Acidification

CO2 + H20 HCO3- + H+

Water becomes more acidic.

(ACID)

Remains in the atmosphere (greenhouse gas)

Dissolves in sea water

CO2

CO2

Over the last 200 years, about 50% of all CO2 produced on earth has been absorbed by the ocean.

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(Royal Society 6/05)

Inundation

Sea level has increased 3.2 mm/year between 1993 and 2008 (IPCC 2007).

This is 10-20 times faster than during the last 3,000 years (ACIA 2004).

0.4-0.6 meters of sea level rise by 2100 if 3 times pre-industrial CO2 or 1% increase/year (Overpeck et al. 2006).

As Greenland and Antarctic ice sheets melt ...

Ocean Nations Threatened

Maldives nation held cabinet meeting 20 feet under water.

Tuvalu nation considering exodus (highest elevation is 15 feet)

New Moore Island goes under in March 2010

Inundation InundationInundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge)

Weiss and Overpeck, 2006

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What We Can DoWhat We Can Do

1. Is it Achievable?

2. Action Is Essential at Every Level

• Individual• Corporate• Local• State• Federal• International

3. Critical Steps

R E D U C E C O 2 E M I S

S I O N S

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1954 2004 2054

14

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1.9

Carbon Emissions(Billions of tons per year)

Current P

ath

At leastTRIPLING

CO2

Avoiddoubling

CO2

Flat Path

STABILIZATION TRIANGLE

What We Can DoIs it Achievable?Is it Achievable?

Pacala and Socolow, Science 2004Glo

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Clicker Question:

The Greenhouse effect would not occur if:

A: The Earth had no atmosphere.

B: The amount of carbon dioxide doubled.

C: We got rid of all the forests.

D: The Earth didn’t have an ocean.

Why is it controversial?

Two Kinds of “Classical” Planets

"Terrestrial"

Mercury, Venus,Earth, Mars

"Jovian"

Jupiter, Saturn, Uranus, Neptune

Close to the SunSmall

Far from the SunLarge

Few MoonsNo RingsMain Elements Fe, Si, C, O, N:we learn that from the spectra

Mostly RockyHigh Density (3.3 -5.3 g/cm3) reminder: liquid water is 1 g/cm3

Slow Rotation (1 - 243 days)

Mostly GaseousLow Density (0.7 -1.6 g/cm3)

Many MoonsRingsMain Elements H, He

Fast Rotation (0.41 - 0.72 days)

Mercury

= 5.4 g/cm3

= 0.38 that of Earth

Mass

Radius

Density

Gravity

= 3.3 x 1026 g= 0.055 M

Earth

= 2439 km= 0.38 R

Earth

Semimajor axis = 0.39 AU

Discovery of Water Ice on Mercury

Goldstone 70m radar received by the VLA

Polar regions could be 125 K and never warmed by the Sun

Orbit of Mercury

3:2 resonance with the sun Orbital period of 88 days Sidereal rotation of 59 days

1 “day” on mercury = 176 earth days

Daytime temp = 500 KNighttime temp = 100 K

Structure of Mercury

And no atmosphere, so no wind or erosion. Surface reflects geologic history well.

(from Mariner 10 and theoretical arguments)

1.Crust 100-200 km thick

2. Mantle 600 km thick

3. Core, 1800 km in radius

Messenger at Mercury in 2011

MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER)

Clicker Question:

We think Mercury could have ice at the poles because:

A: Mercury is so far from the Sun.

B: Optical images show white polar caps.

C: Radar images show high reflectivity at the poles.

D: Mercury is in a 3:2 spin:resonance orbit around the Sun.

Venus

Mass = 0.82 MEarth

Radius = 0.95 REarth

Density = 5.2 g/cm3

Average distance from Sun = 0.72 AU

Orbital period = 225 days

Rotation period = 243 days (longer than orbital period, and retrograde!)

Venus' Atmosphere

- Pressure at surface is 90 x that of Earth's => much more gas in atmosphere. No oceans.

- Consequence - meteoroids burn up easily. No impact craters less than ~3 km. What’s the composition of the atmosphere?

- Hot at surface - 730 K! Almost hot enough to melt rock

- Why so hot? Huge amount of CO2 leads to strong greenhouse

effect.

- 96.5% CO2

- Yellowish color from sulfuric acid clouds and haze.

Early on, T may have been much lower (but still warmer than Earth). Oceans existed?

But if warm enough, T would start to rise because of...

Runaway Greenhouse Effect

1) Water and CO2 evaporate from oceans into atmosphere.

2) Greenhouse effect more efficient.

3) Temperature rises.

4) More evaporation (back to #1).

=> complete evaporation of oceans. Thick atmosphere.

The Habitable Zone or “The Goldilocks Problem”In the zone …

Missions to VenusSoviet Venera 4 -18 (1967 - 1983)

Mariner 2, 5 and 10 (1962, 1967 and 1974)

Pioneer Venus (1978)

Magellan (1989)

Venera 13 photo of surface. Rocks are basalt and granite.Color is due to atmosphere.

Color correctedfor atmosphere.

"Radar Echo" technique measures altitude

space probe

time for signal to return tells you the altitude of surface feature.

Planet Surface

Radar data (Pioneer Venus mission) reveal altitude variations on surface. Flatter than Earth, no evidence for plate boundaries => no large scale plate tectonics.

1 km But plenty of evidence of stresses andfractures on smaller scales => muchsmall-scale shifting of crust

Unlike Moon, larger impact craters distributed randomly over surface => all parts of surface have about same age.

Paucity of large impact craters => surface is young, 200-500 million years?

Impact Craters

Volcanism

Shield volcano elevation map from Magellan radar data. About 100 km across. Volcanism may be ongoing, based on sulfur dioxide variations in atmosphere.But very little resurfacing in past 200-500 million years.

Venus surface flyover

Volcanism

Venus surface flight simulation using data from Magellan.

Clicker Question:

Why is Venus the hottest planet in the Solar System?

A: It is the closest planet to the Sun.

B: There is a lot of radioactive material in the crust.

C: There is a large concentration of carbon dioxide in the atmosphere.

D: The Russians left the lights on in the Venera 5 landing vehicle.

E. Paris Hilton lives there.

Touring Venus

Touring Mars